The present invention relates to an image reading apparatus such as a copying machine, scanner, or facsimile apparatus, and a control program therefor and, more particularly, to an image reading apparatus for reading an original while moving the original with an optical scanning unit being stopped, i.e., a technique of setting the stop position of the optical scanning unit.
As a conventional image reading apparatus such as a copying machine, scanner, or facsimile apparatus, there is known an apparatus having a so-called sheetfed scanning function of reading an original (original information or original image) while moving the original by an ADF (Auto Document Feeder) in a state in which an optical scanning unit for irradiating an original with light is stopped at a predetermined original reading position. The ADF is generally provided as an option, and is detachable from the original reading apparatus main body.
In an image reading apparatus of this type, a desired positional relationship may not be obtained between the ADF and the original reading position in the original reading apparatus main body owing to variations in ADF attaching position and building components.
According to a known method of adjusting the positions, as disclosed in, e.g., Japanese Patent Laid-Open No. 2000-151925, the optical scanning unit is sequentially stopped near an ADF convey roller (platen roller) to irradiate the convey roller with light. Reflected light is read by a photoelectric conversion device such as a CCD image sensor in the image reading apparatus main body. A stop position where reflected light maximizes is set as an original reading position.
According to the conventional method, however, the original reading position may be erroneously detected due to contamination of the platen roller, electrical noise of the original reading apparatus main body, or the like. This leads to image degradation such as a shift of the leading end of an image or a blurred image in original scanning.
The optical scanning unit is sequentially stopped near the ADF platen roller, the platen roller is irradiated with light, and reflected light is read by a CCD. At this time, if the reflected light quantity is small at all stop positions, the erroneous detection probability becomes high.
The present invention has been made to overcome the conventional drawbacks, and has as its object to properly set an original reading position in sheetfed scanning.
To solve the above problem and achieve the above object, according to the first aspect of the present invention, an image reading apparatus is characterized by comprising an optical scanning device which optically scans an original, a moving device which moves a position of the optical scanning device, a photoelectric conversion device which photoelectrically converts an optical image obtained by the optical scanning device, a platen roller which conveys the original, a sheet member which is arranged near the platen roller, a detection device which detects an end position of the sheet member by scanning the sheet member and reading the sheet member by the photoelectrical conversion device while moving the position of the optical scanning device by the moving device, and a setting device which sets, on the basis of a detection result of the detection device, a stop position of the optical scanning device when the original conveyed by the platen roller is read by the photoelectric conversion device while the optical scanning device stops.
According to the second aspect of the present invention, a control program for controlling an image reading apparatus having an optical scanning device which optically scans an original, a moving device which moves a position of the optical scanning device, a photoelectric conversion device which photoelectrically converts an optical image obtained by the optical scanning device, a platen roller which conveys the original, and a sheet member which is arranged near the platen roller is characterized by comprising a detection step of scanning the sheet member while moving the position of the optical scanning device by the moving device, reading the sheet member by the photoelectrical conversion device, and detecting an end position of the sheet member, and a setting step of setting, on the basis of a detection result in the detection step, a stop position of the optical scanning device when the original conveyed by the platen roller is read by the photoelectric conversion device while the optical scanning device stops.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.